It is important in many security, surveillance, sports and other applications to be able to retrieve multimedia data that is of interest in the application. For instance, in a security application where there are numerous video cameras/recorders monitoring a building or other area, it may be necessary to retrieve the video clips corresponding to those times when people moved about in a certain area.
As another example, in a sports broadcasting application, a television producer or a user over the Internet may be interested in getting clips of video corresponding to the times a player was in a certain portion of the playing field. A player or a coach may be interested in looking more closely at those video clips where the player moved in a certain direction in a certain portion of the field.
In such applications, it would be useful to quickly determine where and at which times activities of interest occurred and retrieve a portion (e.g., a few seconds) of video for these corresponding times rather than manually watch several hours of video.
While there has been a large amount of work done in video indexing and retrieval, including work on video retrieval in the context of sports and video surveillance and monitoring, particularly tracking the activity of people in an environment, none of this existing work discloses real time techniques for satisfactorily determining where and at which times activities of interest occurred and retrieving the portions of video for these corresponding times.
For example, in P. Kelly et al., “An Architecture for Multiple Perspective Interactive Video,” Proceedings of ACM Multimedia, pp. 201–212, 1995, techniques are disclosed for determining the best view of an object among views from multiple sensors watching an environment. However, the approach suffers the same drawbacks as mentioned above.
Thus, there exists a need for techniques which overcome the above-mentioned drawbacks by enabling fast and effective retrieval of multimedia data that is of interest in the particular application.